1. Field of the Invention
The present invention relates generally to a depth measuring apparatus, and, more particularly, to a non-destructive measuring mechanism for the depth direction of the interior of a sample.
2. Prior Art
In the field of manufacturing multi-layered bodies for example, the thicknesses of impurity layers, etc., inside the multi-layered bodies have hitherto been tested as part of product quality control.
Conventionally, destructive testing is commonly used in testing the thickness of a specific layer inside this type of multi-layered body. In the prior art, a sample is taken from among products, a cross-section is cut therefrom, and the thickness of the specific layer is measured. Also, conventionally, whether the thickness of the specific layer has attained a predetermined thickness is determined based on the test result of the sample.
However, in the conventional destructive testing described above, the product is destroyed for each testing. As a result, there is room for improvement in terms of reducing the costs incurred in testing. Also, in the above described prior art destructive testing, the individual products are not actually tested, but rather a sampling method is employed. That is, in the prior art, based on the test results of specific samples taken from among a large number of products, the acceptability of the rest of the products is estimated. There is therefore room for improvement in terms of the reliability of testing.
In order to respond to these requirements, development of a technique that can non-destructively test each individual product is strongly desired. However, there is no suitable technique that can solve this requirement in the prior art.